Drugs and driving - what's new?

It's already illegal to drive when you're not fit to do so safely because you're under the influence of drugs - and no bad thing, most of us would say. But this week sees the launch of a new 'drug driving' offence, designed to make our roads safer. The new law doesn't apply in Scotland or Northern Ireland, but of course you can still be arrested if you're not fit to drive.

It's already illegal to drive when you're not fit to do so safely because you're under the influence of drugs - and no bad thing, most of us would say. But this week sees the launch of a new 'drug driving' offence, designed to make our roads safer. The new law doesn't apply in Scotland or Northern Ireland, but of course you can still be arrested if you're not fit to drive.

From now on, police officers with roadside screening tests will start to be deployed, using saliva tests to check for two new groups of drugs. If you test positive, you can be asked to give a blood sample for further testing.

The first of the two new groups of drugs are ones which are used recreationally by some people, but which are also fairly often prescribed by a doctor. They include:

Most of these (the drugs ending in '-epam') are members of the benzodiazepine family of drugs. They can be prescribed for anxiety and insomnia, or sometimes for muscle spasms. But they are highly addictive and are among the most commonly abused drugs I see in my practice - with patients often buying and taking doses many times the maximum recommended. Methadone is used as a substitute for people with an addiction to heroin, and morphine is a very strong painkiller used in cancer and for severe pain from other causes.

The levels for these drugs have been set quite high, so few people on standard prescription doses of these drugs will test positive. If they do, they can offer a statutory 'medical defence' as long as:

The drug was prescribed for medical or dental purposes and

Is being taken at the dose prescribed and according to the written instructions in the accompanying written patient information leaflet and

You don't feel sleepy or otherwise affected. Even if you're taking a drug as prescribed, it's still illegal to drive if your ability to drive safely is affected as a result.

The second group are drugs which are commonly abused. For these, there will be pretty much a 'zero tolerance' approach. They include cannabis, ecstasy, cocaine, LSD, ketamine and heroin. If you have been prescribed one of these (for instance, diamorphine (heroin) or its breakdown products), you can still use the same medical defence as for the first group of drugs. However, if you haven't been prescribed them, you can still be prosecuted even if there's no proof that you were incapable of driving safely as a result.

I've already had patients taking strong painkillers coming in anxious at the prospect of being arrested and convicted. But on the whole, I've been able to reassure them - because with any of the drugs involved in this new law, they should already have had a discussion with their doctor about the possible impact on safe driving. And as long as they've been advised that they're okay to drive, and aren't taking more than prescribed, they have a good defence even if they are stopped. I have, however, started suggesting they might consider keeping proof of their prescription with them in case they are stopped. And I've reiterated my usual advice that:

They shouldn't drive if they feel dizzy, clumsy or sleepy

They should be particularly careful when they first start or increase the dose of certain drugs, because side effects are often worse around this time or

If they've started a different medication which might interact with their existing drugs.

This law isn't about making life harder for you if you're already struggling with a medical condition - it's about keeping the bad guys off the streets.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.